Addition Kinetics and Spin Exchange in the Gas Phase Reaction of the

Additions and Corrections

J. Phys. Chem., Vol. 100, No. 40, 1996 16445

H. Dilger, M. Schwager, P. L. W. Tregenna-Piggott, E. Roduner,* I. D. Reid, D. J. Arseneau, J. J. Pan, M. Senba, M. Shelley, and D. G. Fleming: Addition Kinetics and Spin Exchange in the Gas Phase Reaction of the Ethyl Radical with Oxygen Page 6568. A check in the context of a new experiment at PSI has revealed a faulty composition of the thermocouple. We conclude that our experiment covered a considerably larger temperature range than reported. The corrected values for the rate constants kch for the addition of the ethyl radical to oxygen are 8.5(5) (222 K), 9.3(6) (243 K), 6.8(4) (319 K), 6.2(3) (387 K), and 5.1(3) (475 K) in units of 10-12 cm3 molecule-1 s-1. Revision of Figure 9 shows that our data are now in quantitative agreement with those reported by Kaiser and very close to the theoretical predictions by Wagner et al. The apparent Arrhenius parameters for the range 243-475 K are A ) 2.9(3) × 10-12 cm3 molecule-1 s-1 and Ea ) -2.4(3) kJ mol-1. The results obtained at TRIUMF for the spin exchange rate constant kex and for the pressure dependence of kch remain valid.

Figure 9. Arrhenius plot for kch, comparing the present work with literature data. High-pressure limit (theory,1 solid line), 1 atm of He gas (theory,1 dashed line), Lennard-Jones collision limit (dotted line), 1.5 bar of ethene (present µSR data, filled squares) with high-pressure limit at 294 K (inverse triangle), and collision limit derived from kex (triangle), 1 atm of H2 gas (experimental data by Munk et al.,2 circles), and experimental data by Kaiser3 (hatched rectangles).

References and Notes (1) Wagner, A. F.; Slagle, I. R.; Sarzynski, D.; Gutman, D. J. Phys. Chem. 1990, 94, 1853. (2) Munk, J.; Pagsberg, P.; Ratajczak, E.; Sillesen, A. J. Phys. Chem. 1986, 90, 2752. (3) Kaiser, E. W. J. Phys. Chem. 1995, 99, 707.

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